Breast cancer is the most common cancer in women globally, and tumor size measured as the largest diameter of the tumor focus is currently used in tumor-lymph node-metastasis (TNM) staging for prognosis and treatment decisions. The present study utilized the tumor-to-breast volume ratio (TBR) to evaluate the relative tumor size and determined the prognostic impact of TBR on survival in patients with breast cancer. Two thousand twenty-five consecutive breast cancer patients who underwent modified radical mastectomy between January 2002 and December 2008 at Sun Yat-Sen University Cancer Center were enrolled in this retrospective study. Kaplan-Meier analysis was used to assess the prognostic effect of TBR on cancer-specific survival (CSS), and univariate log-rank test and multivariate Cox proportional hazards regression model were performed to identify independent prognostic factors. The optimal cutoff value of TBR was determined to be 1.70 %, and 1473 and 552 patients were categorized to low-TBR and high-TBR groups, respectively. In the whole patient cohort, CSS was significantly shorter in the high-TBR group (110.2 vs 128.5 months, P < 0.001). Univariate and multivariate analyses revealed that TBR was an independent prognostic factor of CSS in breast cancer patients (hazard ratio (HR) 1.489, 95 % CI 1.130-1.961, P = 0.005). High TBR was independently associated with poor prognosis in breast cancer patients. This variable may serve as a valuable parameter to predict the outcomes of breast cancer.
Keywords: Breast cancer; Mastectomy; Prognosis; Tumor-to-breast volume ratio.